Getting Started with PHP (basic, variable, constant, structure statement)

php Getting Started (basic, variable, constant, structure statement), a friend of the need can refer to. Basic knowledge: ?> can omit string connectors are. Comments//Variables variables must have a first letter of $, a letter or underscore "_" can only be composed of letters, numbers, and "_" can also contain Chinese characters case-sensitive var_dum P "function can display the data type of our variables, we have a trade-in with the" echo "command to Output a Boolean type, if" true "Output is" 1 "," false "then nothing output when the double quotes contain variables, the variables are concatenated with the contents of the double quotation marks; When a variable is enclosed in single quotes, the variable is exported as a string with a long string: delimiter <<< + arbitrary identifier + content + Identifier constant Define defines the system constant (1) __file__:p hp program file name. It can help us get the current file in the physical location of the server. (2) __line__:P the number of HP program file lines. It can tell us the current code in the first few lines. (3) Php_version: The version number of the current parser. It can tell us the current PHP parser version number, we can know in advance whether our PHP code can be parsed by the PHP parser. (4) Php_os: Executes the current PHP version of the operating system name. It can tell us the name of the operating system used by the server, we can optimize our code constants according to the operating system to value directly using the constant name mixed constant (string constant_name);//Returns a variety of information, failure returns the error message bool Defined (string constants_name), determining whether a variable is defined by a reference to a variable & string link operator : =//connection with Assignment Structure statement (1) Only value, do not remove the subscript !--? php foreach (array as value) { //performed task } ?> (2) Remove simultaneously Standard and value !--? php foreach (array as subscript = = value) { //tasks performed } ?>

Php

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